MG Head and Grado?
Nov 16, 2001 at 5:39 AM Post #31 of 41
Quote:

To get further off topic, Grados (SR-60 at least) do require more power than Sennheiser HD600s to reach the same SPL. This is because they are less sensitive (94 dB at 1 mW vs. 97 dB at 1mW). This of course assumes the manufacturers provide accurate ratings.


Then the manufacturers don't provide accurate ratings... I know for a fact that the above isn't true. HD600 require more power than SR60 to reach the same SPL.
 
Nov 16, 2001 at 7:01 AM Post #32 of 41
John:

Wharfedale's are built in England..as such their speaker's LOUDNESS chart uses British terminology. Taking an SPL measurement is easily done. Hence Lorrie.

I left off The "Very faint part:

0db Threshold of hearing
6db Human Breathing
10db rustle of leaves
20db average whisper

This is not MY chart it is Wharfedales from simple measurements.

Yes I am sure that Military applications can go over 200db Like a big ass Bomb going off at one meter.

Again if you ask the professionals that design and build this equipment at www.audioasylum.com they will tell you the same...in this instance you are interpreting the math incorrectly and Gasp...so has the Encyclopedia Britanica.

I have quoted word for word what is said in Wharfedale's speaker's manual on WATTS and on LOUDNESS. As one of the pre-emininant(and longest running) speaker manufacturers in history...they are not wrong.

If you'll notice going from 10db Rustle of leaves in breeze to 70db (typwriter in a print room) is the same as a relative starting point of 140db Near Jet Engine during power take-off to 200db (likely a bomb - which BTW made people instantly deaf by literally blowing their ear drums in WWII...and can cause death. So is that big multimillion times figure implausable...not at all.

Quote:

I know that a 3dB increase in SPL is esentially "twice" the loudness.


No. it's not twice the loudness...it requires twice the power. You are mixing a power calculation with a loudness calculation...they are separate things.

You type in 10Watts(this is not Decibals it's a power figure) so whatever answer you come up with is going to also be a power figure and has nothing to do with volume). You then keyed in the 3db increase that you are after...right...the answer is 2...which is a doubling of POWER not volume. 2 in this case means a doubling as you say but a doubling of Watts(and watts is not decibals).
 
Nov 16, 2001 at 5:20 PM Post #33 of 41
Hey, you are right MacDEF! But not because my calculations were wrong, its just that Grado SR-60s have 98dB sensitivity, not 94dB, doh! It's not my fault though, I got the numbers from AudioAdvisor, those evil bastards.
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The Grado webpage lists all of their models at 98 dB sensitivity, so they indeed would use less power than the HD600. My apologies.
 
Nov 16, 2001 at 7:58 PM Post #34 of 41
DUDE, I NEVER said a THING about plugging power into any "equation". That was YOUR misunderstanding. All I have ever contended was that a 3dB increase is an essentially doubling of SPL. I am not talking about power AT ALL (although I believe that I am correct in that respect as well). I am simply saying that double the SPL = slightly over 3dB. [size=medium]I DO NOT CARE WHAT WHARFEDALE HAS TO SAY ABOUT dB.[/size] They are *gasp* wrong if they do not claim that 3dB is double the SPL. I am sure that they are fine engineers and can do a much better job than me at building speakers any day of the week. HOWEVER, Physics is physics and is not subject to interpretation. Sorry to be so dogmatic, but this is TRUTH. Thank you. I am sure that you are going to reply back to this RGA, but this is my last post....no seriously. You're not going to change my mind, and apparently I am not going to change yours. I hope this does not create any hard feelings between us. That said, I wanna stop before this does occur.

Brett
 
Nov 16, 2001 at 11:39 PM Post #35 of 41
Domer:

Sorry man I thought it was you that did the power calculation but it was slideman or sombody.

It is interesting what you say. If I sit 1 meter away from a speaker that is producing 90db at 1 watt and I move 1 meter back then the volume will be cut by 3db. Therefore...the volume should be cut in almost 1/2 and move 1 more meter and it would be cut in 1/2 again. I have a tough time with that, so it may very well be what I said initially about the PERCEIVED volume level - which may be a different beast all together.
 
Nov 17, 2001 at 2:01 AM Post #36 of 41
The problem in the calculations is that a 3db difference does not double loudness. It takes a 10 db difference to cause loudness to double.Check page 47 of The Master Handbook of Acoustics, 2nd Ed. by F. Alton Everest. With that correction you both can be correct and peace can once again reign oer the land of HeadFi.
 
Nov 17, 2001 at 6:38 AM Post #38 of 41
Morphsci:

This is what I said at the beginning. 10db is a double in loudness...I just checked it over at audioasylum.

jj is the resident expert here so:

First off, dB is defined as 10 log10 (P1/P0) where P1 and P0 are POWERS. That means that doubling the power is 3.01dB, give or take. Now, if we want to calculate the same thing using amplitude, instead of power, the equation is 10 log10 ( (a1/a0)^2 ) which is directly equal to 20 log10 (a1/a0). A change of 2x in amplitude is the same as a change of 4x in power (2^2), i.e. 6.02 dB.
So much for both of these measures, which express the ratio of powers or amplitudes. Both are measuring the ratio change of something properly known as INTENSITY, i.e. the measured, physical, external size of the simulus.

Now ... LOUDNESS is the term for internal, percieved sounds. Loudness goes as about the .25 power or so (there are many exceptions and complications to this, and the number is also frequency sensitive) of the power. So when something gets 10dB more intense, it gets about 2.5 sones louder, or about twice as loud.


JJ

So Domer is definitely correct about the mathematical aspect and I'm corrsect about what is needed for us poor pathetic human beings to PERCEIVE a doubling of volume.

See That Damn word PERCEIVE: I told you it would be a big pain in the rear.

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